To reclaim supremacy in the NFC West, Kyle Shanahan may just have to find a way to beat … himself?

Since the San Francisco 49ers last finished on top of the division, the landscape has changed. It’s no longer just Shanahan and Sean McVay finding the next frontiers in how to pre-snap motion defenders into a blender. Their fingerprints are all over the whole division.

In Seattle, former 49ers assistant Brian Fleury is calling plays in an offense installed by Klint Kubiak, another branch on the Shanahan coaching tree. And on Sunday afternoon, the offense that the Arizona Cardinals will run Sunday at Levi’s Stadium should look mighty familiar.

After finishing a dismal 3-14 last season, they gave the axe to Jonathan Gannon, looked around the rest of the league and decided to get in on the trend … put in motion … by Shanahan and McVay a decade earlier. Ahead of running into yet another former staffer in Mike LaFleur on the opposing sideline, Shanahan was asked if he takes any pride in seeing his coaching tree sprout.

“Deep down probably yeah, and eventually,” the 10th-year head coach said. “But, it’s more irritation, especially when you have to run into them twice a year.”

Shanahan, increasingly gray in the hair, is growing into somewhat of a godfather figure of the modern offense. The Niners will face his system in some form or another in each of their first three games and for four of their first five weeks of the season.

Of course, it’s all rooted in Bill Walsh’s West Coast offense, which Shanahan’s father, Mike, learned through poring over the tape of the legendary 49ers coach installing it himself. The elder Shanahan eventually took the system to Washington, where he passed it on to Kyle (and Sean).

On Sunday, Shanahan will coach his 166th game with the 49ers, matching Walsh’s record for the most regular-season and playoff games coached in franchise history.

Shanahan never met Walsh, but soon after taking the job in 2017 he said he was inspired by his dad and “entertained myself” with the old tapes of Walsh in the 49ers’ locker room.

It’s only fitting that it will come against another coach to whom Shanahan passed down the playbook. As far as X’s and O’s go, that would have to give Shanahan the upper hand, right?

“Talk about all the movement, the eye candy,” linebacker Fred Warner said. “You’re having to communicate a ton just to make sure everybody’s on the same page. But the beauty in it is obviously we’ve gone against it for so long.”

On the other hand, if everyone is running some version of the 49ers’ playbook, wouldn’t that also mean they’re practicing against it, too? At least according to tight end George Kittle, the route trees are unrecognizable from LaFleur’s time as passing game coordinator from 2017-20.

“Everything’s so different now. All of our motions, gaps. How we structure plays – everything’s so different,” Kittle said. “Kyle’s offense has grown so much and changed so much that I think a lot of these guys haven’t seen what he’s done the last couple of years.”

LaFleur spent the last couple of years running McVay’s offense with the Rams, where he went head-to-head with Raheem Morris’ defense everyday in practice on their way to the Super Bowl in 2023. And vice versa for Morris, now the 49ers’ defensive coordinator.

LaFleur’s offense made a splash in Week 1, putting up almost 400 yards in a surprising 26-14 win over the Chargers. It ran into a buzzsaw in the Seahawks’ defense last week, mustering a mere 151 total yards — just 95 on 28 Jacoby Brissett pass attempts — in a 31-7 loss.

“I thought the game last week was a lot closer than the score indicated,” Shanahan said. “Just the style of offense they’re doing, it’s similar schematically to the Rams, but they’re blocking hard, they’re running hard, guys are really competing. … They have a lot more talent than people give them credit for and I know Mike’s going to have them ready to go.”

It isn’t quite the well-oiled machine that the 49ers are in their 10th season under Shanahan, and nobody is expecting LaFleur to turn the Cardinals into contenders overnight when they’re competing against arguably the three best teams in football in their own division.

That at least puts Arizona front and center to the outcome of the most hotly contested division in the NFL. If we assume the 49ers, Seahawks and Rams are so evenly matched that they all split against each other, one trip-up against the Cardinals could prove to be fatal in the division race.

Seattle already took care of business on the road with its backup quarterback last week.

The 49ers can’t afford to take LaFleur and the Cardinals lightly.

Because you know he won’t in his first game back at Levi’s as a head coach.

“[He] knows Shanahan. He knows Raheem. He knows everything that we’re about. He was here when we put the foundation together,” Kittle said. “He’s gonna want nothing more than to beat Kyle Shanahan and the San Francisco 49ers.”